Dynamo brush-holder.



J. L. WOODBREDGE.

DYNAMO BRUSH HOLDER.

APPLICATION FILED ocr. 29. 1915.

1 ,285, 874. Patented Nov. 26, 1918.

Josef/1 [a 622i n dadn'dya lwuemw CLA M G ISW Mowm UNITED STATES PATENT OFFICE.

JOSEPH LESTER WOODBRIDGE, 0F PHILADELPHIA, PENNSYLVANIA.

DYNAMO BRUSH-HOLDER.

Application filed October 29, 1915.

To all whom it may concern:

Be it known that I, JOSEPH LESTER WOOD- BRIDGE, a citizen of the United States, and a resident of the city of Philadelphia, in the State of Pennsylvania, have invented certain new and useful Improvements in Dynamo Brush-Holders, of which the following is a specification.

My invention relates to brush holders for dynamo electric machines in which the brush is held in place by fixed guides, and pressure is applied by means of a spring to hold the brush in proper contact with the com mutator or collector ring. The object of my invention is to provide simple and inexpensive means for applying the pressure of the spring radially with respect to the commutator and eliminating any tendency to rock the brush or produce unequal pres- ;ure at different parts of the contact surace.

My invention is illustrated in the accompanying drawings, in which Figure 1 is a view of a brush holder involving features of my invention, while Fig. 2 is a view of the same brush holder partly in section taken at right angles to Fig. 1.

In the drawings, 1 represents the commutator, 2 is a brush bearing upon the commutator, 3 is a fixed brush holder having guides 8 near the surface of the commutator between which the brush 2 is free to slide radially with respect to the commutator. The brush 2 is provided at the top with a V-shaped notch or seat 4: at the bottom of which one end of the fiat coiled spring 5, bent into radial relation, applies the necessary pressure to keep the brush in contact with the commutator. The opposite end 9 of this spring is rigidly attached to the free end of a stirrup 6 which at its other end is pivoted to a horizontal bar 7 supported by the brush holder. The bar 7 is located radially with respect to the commutator in line with the axis of the brush. With this construction it will be seen that the reaction exerted by the spring and the stirrup against the brush and'the bar 7 must always be in a line passing through the axis of the bar and the free end 10 of the spring. This line be- Specification of Letters Patent.

Patented Nov. 26, 1918.

Serial No. 58,584.

ing radial with respect to the commutator, the pressure on the brush will always be radial. This arrangement is of special ad vantage .where the direction of rotation of the commutator is periodically reversed inasmuch as it allows the brush to move freely between the guides 8 in the direction of commutator rotation with reversal of said rotation without any tendency to tilt the brush in either direction, or to bring excessive pressure on one edge or the other of the contact surface of the brush. With such motion of the brush the stirrup 6 will rock slightly in either direction about the bar- 7 to which it is pivoted.

The arrangement shown also permits a spring of considerable length to be used in a minimum space, thus maintaining comparatively uniform pressure as the brush wears and its length is reduced. Furthermore, that part of the device that moves with radial motion of the brush is the free end of the spring, which is comparatively light and introduces but little inertia to prevent the brush from following any irregu-- larities of the commutator at high speed. Obviously the stirrup may be pivoted on the bar 7, or the bar may be pivoted in the brush holder without altering the principle involved. Other obvious changes in the details of construction may be made without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

In a current collecting device the combination of a stationary frame, a brush loosely guided by said frame, a rigid link pivoted to one end of the frame in the axis of the brush, and a spring having one end bearing axially on the brush and free to move laterally therewith and having its other end attached to the free end of the link substantially as described.

In testimony whereof, I have hereunto signed my name.

JOSEPH LESTER WOODBRIDGE.

Witnesses:

J OSEPH H. TRACY, R. A. WHITSTONE, Jr.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

